From: Eric Dumazet edumazet@google.com
stable inclusion from stable-v5.10.94 commit edc09548ffc52433ed25ef4a829e664e353f615d bugzilla: https://gitee.com/openeuler/kernel/issues/I531X9
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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commit 91341fa0003befd097e190ec2a4bf63ad957c49a upstream.
Both fields can be read/written without synchronization, add proper accessors and documentation.
Fixes: d5dd88794a13 ("inet: fix various use-after-free in defrags units") Signed-off-by: Eric Dumazet edumazet@google.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com Acked-by: Xie XiuQi xiexiuqi@huawei.com --- include/net/inet_frag.h | 11 +++++++++-- include/net/ipv6_frag.h | 3 ++- net/ipv4/inet_fragment.c | 8 +++++--- net/ipv4/ip_fragment.c | 3 ++- 4 files changed, 18 insertions(+), 7 deletions(-)
diff --git a/include/net/inet_frag.h b/include/net/inet_frag.h index bac79e817776..4cbd413e71a3 100644 --- a/include/net/inet_frag.h +++ b/include/net/inet_frag.h @@ -116,8 +116,15 @@ int fqdir_init(struct fqdir **fqdirp, struct inet_frags *f, struct net *net);
static inline void fqdir_pre_exit(struct fqdir *fqdir) { - fqdir->high_thresh = 0; /* prevent creation of new frags */ - fqdir->dead = true; + /* Prevent creation of new frags. + * Pairs with READ_ONCE() in inet_frag_find(). + */ + WRITE_ONCE(fqdir->high_thresh, 0); + + /* Pairs with READ_ONCE() in inet_frag_kill(), ip_expire() + * and ip6frag_expire_frag_queue(). + */ + WRITE_ONCE(fqdir->dead, true); } void fqdir_exit(struct fqdir *fqdir);
diff --git a/include/net/ipv6_frag.h b/include/net/ipv6_frag.h index 851029ecff13..0a4779175a52 100644 --- a/include/net/ipv6_frag.h +++ b/include/net/ipv6_frag.h @@ -67,7 +67,8 @@ ip6frag_expire_frag_queue(struct net *net, struct frag_queue *fq) struct sk_buff *head;
rcu_read_lock(); - if (fq->q.fqdir->dead) + /* Paired with the WRITE_ONCE() in fqdir_pre_exit(). */ + if (READ_ONCE(fq->q.fqdir->dead)) goto out_rcu_unlock; spin_lock(&fq->q.lock);
diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c index 10d31733297d..e0e8a65d561e 100644 --- a/net/ipv4/inet_fragment.c +++ b/net/ipv4/inet_fragment.c @@ -204,9 +204,9 @@ void inet_frag_kill(struct inet_frag_queue *fq) /* The RCU read lock provides a memory barrier * guaranteeing that if fqdir->dead is false then * the hash table destruction will not start until - * after we unlock. Paired with inet_frags_exit_net(). + * after we unlock. Paired with fqdir_pre_exit(). */ - if (!fqdir->dead) { + if (!READ_ONCE(fqdir->dead)) { rhashtable_remove_fast(&fqdir->rhashtable, &fq->node, fqdir->f->rhash_params); refcount_dec(&fq->refcnt); @@ -321,9 +321,11 @@ static struct inet_frag_queue *inet_frag_create(struct fqdir *fqdir, /* TODO : call from rcu_read_lock() and no longer use refcount_inc_not_zero() */ struct inet_frag_queue *inet_frag_find(struct fqdir *fqdir, void *key) { + /* This pairs with WRITE_ONCE() in fqdir_pre_exit(). */ + long high_thresh = READ_ONCE(fqdir->high_thresh); struct inet_frag_queue *fq = NULL, *prev;
- if (!fqdir->high_thresh || frag_mem_limit(fqdir) > fqdir->high_thresh) + if (!high_thresh || frag_mem_limit(fqdir) > high_thresh) return NULL;
rcu_read_lock(); diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c index cfeb8890f94e..fad803d2d711 100644 --- a/net/ipv4/ip_fragment.c +++ b/net/ipv4/ip_fragment.c @@ -144,7 +144,8 @@ static void ip_expire(struct timer_list *t)
rcu_read_lock();
- if (qp->q.fqdir->dead) + /* Paired with WRITE_ONCE() in fqdir_pre_exit(). */ + if (READ_ONCE(qp->q.fqdir->dead)) goto out_rcu_unlock;
spin_lock(&qp->q.lock);